The first prime that can be written as a sum of composites in more ways than it can be written as a sum of primes. [Hartley]

The first prime in the decimal expansion of the Gauss's constant G, defined as the reciprocal of the arithmetic-geometric mean of 1 and sqrt(2). Note that G =
0.83462684167.... [Capelle]

83 is the sum of the first three primes ending with the digit one. [Sladcik]

The United States Navy ship "Pueblo" had a crew of 83
men on-board when it was seized by North Korea. [Dobb]

Find the average of all primes up to 83 and you'll get the reversal of 83.

The German mental calculator Rüdiger Gamm (1971- ) once demonstrated his ability on an Australian radio show by calculating consecutive powers of 83 in his head without making a mistake. The number 83 had been selected for him randomly.

The mean of all primes less than or equal to 83 equals the reversal of 83. [Honaker]

Vanuatu is an archipelago of 83 islands lying between New Caledonia and Fiji in the Southwest Pacific.

Total number of vertices in all finite 6-dimensional
regular polytopes (7 in the 6-simplex, 64 in the
6-hypercube, 12 in the 6-hyperoctahedron). [Post]

The Irish born figurative painter Francis Bacon died in
1992 at the age of 83. Note that 1992 hours is exactly 83
days.

Bismuth, number 83 on the periodic chart, is the heaviest
element that is not radioactive. [Conway]

If you write all primes up to 83, then you can see nine digits 1, ..., 9. [Poo Sung]

The largest known prime number p such that 2p does not contain the prime digit 2. [Capelle]

The optimum temperature (in degrees Celsius) for preparing custards made of one
egg, one cup of milk, and one tablespoon of sugar. [Beedassy]

The only two-digit prime that is the arithmetic average of
three consecutive emirps (73, 79, and 97). [Silva]

The largest known prime number that can be expressed as the
sum of three positive triangular numbers in exactly one
way. [Capelle]

The smallest prime exponent in the size of the free
cartesian closed category over 3 objects. 3^83 is thus an
upper bound on the number of left-associated formulas in
Michael O'Connor's "An Interesting Puzzle in Propositional
Logic." [Post]

Robert Peary estimated "Crocker Land" to be at about 83 degrees latitude.

The dot product of the vector whose components are the 4th
row of Pascal's Triangle and the vector whose components
are the first 5 primes in order. [Green]

(83, 89, 97) is the larger of only three known cases of successive primes p < q < r such that p|(qr-1), i.e., the smallest prime divides the product of the other two minus 1, (83 divides 89*97-1). The previous two cases are (2, 3, 5) and (11, 13, 17). [Loungrides]